Air quality sensor/interruptor

ABSTRACT

An air quality sensor and interrupter system includes an air quality sensor to measure the air quality around a gas appliance and an appliance shut-off device to turn off the gas appliance in response to a signal from the sensor indicating unsafe air. Unsafe air can be indicated by a measurement of 18.5% or less oxygen in the air.

CROSS REFERENCE TO RELATED APPLICATIONS

The present invention claims priority to U.S. Provisional Application Serial No. 60/671,952, filed Apr. 15, 2005, and which is incorporated by reference in its entirety.

BACKGROUND

1. Field of Invention

The present invention relates generally to air quality detection systems, and in particular, to such systems that take action based on the air quality detected.

2. Related Art

Gas appliances can generate unsafe levels of various gases, such as carbon monoxide (CO), into the air. Such gases need to be detected so that people within the air space do not get ill or suffer any other health-related problems. For example if a burner system in a gas appliance is not burning properly, unsafe levels of combustion by-products are released into the environment because of incomplete combustion.

One type of gas detection system uses the oxygen detection safety-pilot (ODS) technology on gas appliances. A typical ODS pilot system includes an oxygen-sensitive pilot burner that regulates flame characteristics, a thermocouple positioned in the mantle of the pilot flame, and a safety shut-off valve. The pilot flame is designed to be stable within a very narrow operating range. The thermocouple responds to changes in the pilot flame characteristics and, when heated, generates a voltage, e.g., in the millivolt range, which keeps the gas supply valve in the open position.

However, if low levels of oxygen are detected by the ODS system, the flame extinguishes. The loss of flame causes the thermocouple to cool. This cooling reduces the voltage, which causes the gas valve to return to its normally closed position, thus turning off the fuel supply to the appliance. The unit will not operate until the space is properly ventilated and adequate oxygen is introduced, and the appliance is restarted.

Although relatively effective, there are several inherent problems with ODS systems. These include, but are not limited, to susceptibility to drafts, pilot positioning, gas supply, orifice sizing, and heating value of the gas. Due to the nature of the ODS pilot system, it is subject to nuisance shutdowns from overheating conditions on the thermocouple cold junction.

Therefore, there is a need for an air quality detection system that overcomes the disadvantages of conventional systems discussed above.

SUMMARY

According to one aspect of the invention, an air quality sensor/interrupter includes an air quality sensor and a means of interrupting the operation of the appliance when a low air quality is detected. In one embodiment, when the oxygen level is approximately 18.0% or lower, a signal is sent to the shut-down mechanism to shut down the gas appliance.

The air quality sensor/interrupter is a device that measures air quality in a confined space, and if unsafe air is detected, shuts down the appliance(s) affecting the air in the monitored space. The sensor may communicate to the interrupter or shut-down mechanism by a wired or a wireless system. Upon receipt of the signal, the interrupter will stop the flow of power, gas, or electricity to the heating element of the appliance(s). In one embodiment, the interrupter may shut down only the heater or burner element of the system and allow the rest of the appliance to function, such as blowers and lights. The appliance is not turned back on until the interrupter or system is reset, either by the user or automatically upon detection of “safe” air.

Thus, because the air quality sensor/interrupter measures the actual air quality in the space and shuts down the appliance based on a detection of unsafe air, the present invention does not have many of the inherence problems of conventional ODS systems.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a block diagram of an air quality detection/shut-down system according to one embodiment; and

FIG. 2 is a flow chart showing steps for shutting down an appliance when unsafe air is detected according to one embodiment.

Embodiments of the present invention and their advantages are best understood by referring to the detailed description that follows.

DETAILED DESCRIPTION

According to one embodiment of the present invention, a sensor is used to measure the quality of air in a room or area. If the measurement indicates unsafe air, a signal is sent to a shut-down device, which then shuts down the appliance or appliances in the monitored air space.

The sensor may employ one of several known technologies and products, such as electromechanical, semiconductor, catalytic bead, and zirconia lambda. Suitable sensors or detectors include the TX-2000 Toxic Gas and OX-2000 Oxygen Intrinsically Safe series of detectors from Enmet Corporation of Ann Arbor, Michigan. These detectors are capable of continually monitoring toxic gases or oxygen and indicating when a certain gas is detected or a certain gas has reached a threshold, such as by an audio alarm or visual display. Gases that can be monitored include, but may not be limited to chlorine (Cl₂), carbon monoxide (CO), hydrogen (H₂), hydrogen sulfide (H₂S), ammonia (NH₃), nitrogen oxide (NO), nitrogen dioxide (N0₂), oxygen (O₂), and ozone (O₃).

In one embodiment, when the sensor detects low oxygen levels, such as at 18.0% or less, an alarm will sound and a signal will be sent to a shut-down device or interrupter. The signal can be sent along a wired channel, such as along a wire, or through a wireless communication. An example of a wireless shut-down device is a RR-1 or RR-1A remote system receiver and transmitter from the Robert H. Peterson Company, the City of Industry, California. The RR-1 or RR-1A system can be modified to act as transmitter and receiver grounding device.

Thus, once a signal is received indicating that the quality of the air has dropped below an acceptable level, the grounding circuit will activate or close and either directly ground the thermocouple/thermopile/battery or magnet power circuit. This would then result in the magnet/valve dropping out or shutting off, causing the gas appliance to shut down. Alternatively, a remote transmitter may be activated to send a signal to a grounding system which would shut down the gas appliance.

FIG. 1 is a block diagram showing one embodiment of the just-described invention. In FIG. 1, an air quality sensor and control system 100 is shown in use with a gas appliance 102. Gas appliance 102 is shown as a gas log system, although any suitable gas appliance can be used with the present invention. Gas appliance 102 is connected to a receiver 104, which operates to receive signals and in response to the signals, turn gas appliance 102 off or on. Receiver 104 receives signals transmitted by a transmitter 106. Signals can be transmitted wireless or over a wired connection. Receiver 104 and transmitter 106 are conventional components to a system, such as the Model# RR-1 or RR-1A kit from the RH Peterson Co. of the City of Industry. An oxygen sensor 108 is connected to transmitter 106. The sensor may be located in the whole house or room area dependent on the sensitivity of the detector. Multiple detectors may be required in a whole house situation.

When oxygen sensor 108 detects low oxygen, e.g., 18.0% or lower, or a toxic gas, it sends a signal to transmitter 106. In response, transmitter 106 sends a turn-off signal to receiver 104. Receiver 104 then turns off gas appliance 102, such as by closing a hot lead/ground circuit 110 in gas appliance 102. In one embodiment, only the burner or gas supply is shut down, while leaving other components of the appliance functional. In other embodiments, all functions or components of the appliance are shut down upon receiving indication of low oxygen environment or toxic air quality.

FIG. 2 is a flowchart illustrating steps for shutting down a gas appliance, according to one embodiment of the present invention. In step 200, the quality of the air proximate to the gas appliance is sensed or measured. Sensing can be with any conventional air quality sensor to detect oxygen levels in the air or to detect the presence of toxic gas. In step 202, a determination is made whether the air quality is safe. In one embodiment, unsafe air quality occurs when the oxygen level is approximately 18.0% or lower. If an unsafe air quality is detected, as determined in step 202, a signal is sent, in step 204, to a device or system for turning off the gas appliance. The device or system may comprise of a transmitter/receiver pair or a single transceiver. If the air quality is not classified as unsafe, then no signal is sent and the gas appliance continues its normal operation in step 206. In step 208, upon receipt of a signal indicating unsafe air quality, the gas appliance is shut down or turned off, either in whole or only specific parts, such as the gas burners. The gas appliance remains shut down until the quality of air is no longer unsafe.

As a result, the gas appliance does not continue generating fire or producing unsafe air, such as with an excess of carbon monoxide, when unsafe air is detected without being dependent on the pilot light. Consequently, reliance on the pilot light is eliminated, thereby eliminating disadvantages of conventional systems using the pilot light.

Having thus described embodiments of the present invention, persons skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the invention. 

1. An air quality sensor and interrupting system, comprising: an air quality sensor configured to measure the quality of air proximate to a gas appliance and generate a signal when unsafe air is detected; and a gas shut off device configured to turn off at least one portion of the gas appliance in response to the signal sent from the air quality sensor.
 2. The system of claim 1, wherein the gas shut off device comprises: a transmitter configured to receive the signal from the sensor and transmit a second signal; and a receiver configured to receive the second signal and to shut off the gas appliance in response.
 3. The system of claim 2, wherein the transmitter and the receiver are in wireless communication.
 4. The system of claim 1, wherein the at least one portion comprises a fuel outlet of the fossil fueled appliance.
 5. The system of claim 1, wherein the fueled appliance is an indoor gas appliance.
 6. The system of claim 1, wherein unsafe air is detected if the oxygen level of the air is approximately 18.0% or less.
 7. A method for operating a gas appliance, comprising: sensing an air quality of air proximate to the gas appliance; determining whether the air quality is unsafe; and turning off at least a portion of the gas appliance if the air quality is unsafe.
 8. The method of claim 7, wherein the gas appliance is an indoor fossil fueled appliance.
 9. The method of claim 7, wherein the sensing comprises measuring an oxygen level in the air.
 10. The method of claim 9, wherein the air quality is determined as unsafe if the oxygen level is approximately 18.0% or less.
 11. The method of claim 7, turning off comprises shutting down a gas outlet of the gas appliance.
 12. The method of claim 7, further comprising keeping the gas appliance turn off until the air quality is no longer determined unsafe.
 13. The method of claim 7, further comprising sending a signal to turn off the gas appliance.
 14. The method of claim 13, wherein sending the signal comprises: sending a first signal indicating unsafe air quality; sending a second signal indicating the gas appliance is to be turned off; and sending a third signal to turn off the gas appliance.
 15. The method of claim 14, wherein at least one of the first, second, or third signals is sent wirelessly.
 16. A system for operating a gas appliance, comprising: means for measuring an air quality of air proximate to the gas appliance; and means for turning off at least a portion of the gas appliance if the measured air quality is determined unsafe.
 17. The system of claim 16, wherein the gas appliance is an indoor gas appliance.
 18. The system of claim 16, wherein the means for measuring measures an oxygen level in the air.
 19. The system of claim 18, wherein the air quality is determined as unsafe if the oxygen level is below a predetermined threshold.
 20. The system of claim 16, further comprising means for transmitting signals to the gas appliance for turning off the gas appliance. 